PLA-based blends were prepared with different ratios of PBS, PBAT and TPS additives to adjust their mechanical and processing properties in various temperatures ( − 20 °C, 0 °C, 20 °C, 40 °C). Biodegradable polymeric specimens were obtained by preliminary extrusion and subsequent injection molding. Tensile properties, e.g., tensile strength, elongation at break, Young’s modulus and yield strength were evaluated. Next, melt flow and melt volume ratios were established. Softening, glass transition, cold crystallization and crystallization temperatures were determined with the use of the DSC method. Heat Deflection Temperatures for 1.8 MPa (HDT A) and 8 MPa (HDT C), as well as Vicat Softening Temperatures at 10 N (VST A) and 50 N (VST B), were examined. The manufacturing method was intentionally simplified to eliminate the need for additional mixture’s modification with compatibilizers. Each of the ductile compounds enhanced the deformability of PLA—most significantly in the case of PBAT and TPS, while at the same time reducing its tensile strength. The effect of the test conditions (strain rate and temperature) on the specimens was evaluated in order to determine the stability of the manufactured blends in dependence on these parameters.

Cork is a sustainable material with remarkable properties. In addition to its main application as wine stoppers, it has also been employed as a sound and thermal insulator in facades, building roofs, aeronautical applications, and, more recently, in impact energy absorption systems. In its natural form, cork is mainly used in wine stopper manufacturing, but for other applications, cork compounds are usually employed, which makes it possible to manufacture complex geometries with nearly isotropic behavior. In this work, an attempt was made to merge the desirable properties of two different cork materials (agglomerated and expanded black) into cork composite sandwich structures. These structures were tested according to impact conditions typically experienced by energy-absorbing liners used in personal safety devices. Additionally, the performance dependency on the working temperature was analyzed. The sole black, expanded cork (EC159) and agglomerated cork (AC199A and AC216) were tested in 500 J impacts. It was found that black cork was characterized by superior thermal stability, while expanded cork allowed absorbing high energies. In the second stage, the composites consisting of both tested materials were tested in 100 J impact scenarios. The combination of two materials of different properties enabled reduction of the peak force exerted on a helmet user’s head during the impact by about 10% compared to agglomerated specimens. Additionally, it was proved that there was no influence of the glue used to join different cork types.

The article presents the results of the development works and research on the atomization process carried out using two prototype high-power ultrasonic systems. Ultrasonic systems have been designed to develop a new metal powder production process; these materials are increasingly used in modern manufacturing processes such as additive technologies or spraying and surfacing processes. The preliminary studies presented in the article were conducted for water to assess the effectiveness of both systems and to verify the theoretical and structural assumptions. In ultrasonic atomization, the ultrasonic wave causes the phenomenon of cavitation, which leads to the overcoming of the surface tension forces of the liquid and its disintegration into fine droplets. The important parameters that affect the properties of the produced droplets include, among others, the frequency of the sonotrode vibrations and the amplitude of the vibrations of the working plate. As part of the research, the paper presents the process of selecting the sonotrode geometry for two different values of the transducer’s natural frequencies (20 kHz and 70 kHz). In the design process, the finite element method was used to perform a harmonic analysis and develop the geometry of the sonotrode and the working plate. The design assumptions and the design process were presented. The modeled and then ultrasonic waveguides were verified experimentally by measuring the deflection distribution on the working plate surface using a high-precision laser displacement sensor. Then, the work ultimately resulted in conducting atomization tests of water. The obtained aerosols and the mechanism of their formation were studied using a high-speed camera. Finally, using Matlab R2020a software and image analysis scripts, it was possible to analyze the droplet size distribution generated by both systems. It was observed that 50% of the produced droplets were in the range of 35–55 μm for a 20 kHz system, while for a 70 kHz system it was 10–25 μm, which is a very satisfying distribution in terms of metal powder atomization.

The use of cork for a variety of applications has been gaining significance due to environmental concerns and political agendas. Consequently, its range of applications is growing rapidly. In this work, aiming to improve its mechanical response for crashworthiness applications, cork agglomerates were enriched by small quantities of graphene oxide or graphene nanoplates in order to observe a resulting improvement of the mechanical behaviour during quasi-static and dynamic compressive loading cases. To produce homogenous cork agglomerates including graphene, the material was previously dispersed into granulated cork using stirrers to achieve a good distribution. Then, the typical procedure of compression and curing was carried out. Magnified images attest a good dispersion of graphene into the cork matrix. Mechanical testing was performed for a variety of graphene concentrations (0.1, 0.5 and 1.0 weight %), becoming clear that the beneficial effect of including graphene (either oxide or nanoplates) is related to a later densification stage while keeping the same stress plateau levels.